The cooling of fluids is desirable in many applications. Internal combustion engines run more efficiently if relatively high temperature fuel is cooled before being introduced into the combustion chamber. Advantageously, emissions are reduced and fuel usage is reduced.
Hydraulic systems function better with cooler hydraulic fluid. Oil lubrication systems are more effective when the oil is cooled. This is true in transmissions and other parts of a power train as well as for the internal lubrication of an engine.